Heat 1 T. oil in a pan with butter and sauté the onions/mushrooms on medium low until nicely colored.
Season the brisket generously with salt/pepper/garlic powder.
Heat the rest of the oil in a heavy bottom pot and sear the brisket on both sides to brown to a golden crust.
Sprinkle the garlic over the brisket and lay it in the crockpot, fatty side up.
Pile the onions on top of the meat.
Mix broth with 2 sauces and pour over the meat.
Cook on low 9-10 hours. Looking for 211° internally for shredding.
Remove slice across the grain. Should fall apart! Mmmm!
Serve with the gravy created in the crockpot!
Slice against the grain.
Excellent served with roasted carrots and potatoes! Even better-we turn these into birria tacos!